LD is found in all cells of the body, with extremely high levels found in specific tissues such as the heart, liver, kidneys, skeletal muscle, and erythrocytes. Therefore, increased levels seen in the serum can be directly related to damage of one of these tissues. Tissue levels of LD are 500-fold higher than whole blood levels. Total LD can be used to differentiate myocardial infarction, in which total LD is three to four times normal, from angina and periocarditis, in which LD levels are normal.